The invention relates to a plan sifter for the sifting or sieving of mealy or granular products, which consists of at least one compartment. The invention also relates particularly to a drive for a plan sifter.
Plan sifters for the sifting of mealy or granular products in mills, in particular in corn mills, are in very widespread use. They have a closable housing with at least one stack of sieves which are arranged one above the other and the covering of which has a mesh width decreasing from the top downwards, so that products of the same particle size ranges can be brought together. For executing the sieving movement, the plan sifter is set in uniformly oscillating motion by means of an unbalance drive.
When a plurality of sieving compartments are arranged in an even number, arrangement may take place in two rows, the drive being arranged between the two rows, as disclosed, for example, in DE 2256307. Furthermore, for example, arrangements of two blocks of four screening compartments with a drive unit lying between them are known (EP-A-1396289).
In order to utilize the space in the drive compartment more effectively, it has also been proposed to arrange sieving compartments at the ends thereof and thus form a closed ring arrangement of sieving compartments (DE 197 46 678). Disadvantages are both the poor access to the drive and unequal motion conditions.
Moreover, in all the variants, only even-numbered multiples of sifting compartments can be arranged to form a plan sifter.